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Väkevien sinkkipitoisten vesiliuosten termodynaamiset ominaisuudet
No full textAbstractZinc is a common metal, and has a central role in the production of galvanised bulk products, battery applications and fertilisers. Its production relies mainly on the leaching of zinc minerals with sulfuric acid, followed by purification and electrowinning. In this thesis an internally consistent thermodynamic model for the industrially important ZnSO₄-H₂SO₄-H₂O system was developed. Model parameters were optimised using available literature data and new experimental freezing point and density data determined in this work. With Gibbs energy minimisation algorithms embedded in commercial software, such as ChemSheet and FactSage, the developed model can be used to calculate easily phase equilibria and thermodynamic properties of aqueous zinc sulfate solutions and solid zinc sulfate phases, including activity coefficients, enthalpy changes, heat capacities, densities and solubilities, in a wide range of temperature, pressure and sulfuric acid concentrations. Solution non-ideality was treated with the original Pitzer model with electrostatic mixing terms included.Applicability of thermodynamic approach and the developed model was demonstrated by two separate case studies on the hydrometallurgical zinc process. Precipitation of amorphous silica during hot acid leach was studied experimentally. Its solubility in the process solution was also successfully predicted using the thermodynamic approach. To study crystallisation of gypsum during the gypsum precipitation stage, the model was expanded by addition of the Ca²⁺ ion. The model calculations showed good agreement with the experienced Ca²⁺ levels.The results of this thesis have found immediate use in understanding the various stages of the electrolytic zinc process. The obtained results also form a basis on which new, more advanced tools for managing and studying the process can be developed.Original papersOriginal papers are not included in the electronic version of the dissertation.Vielma, T., Salminen, J., & Lassi, U. (2018). Thermodynamics of the ZnSO4–H2SO4–H2O system. CALPHAD, 60, 126-133. https://doi.org/10.1016/j.calphad.2017.12.006Self-archived versionVielma, T., Salminen, J., & Lassi, U. (2019). Freezing point depression in the ternary ZnSO4-H2SO4-H2O system. The Journal of Chemical Thermodynamics, 132, 276–280. https://doi.org/10.1016/j.jct.2018.12.043Self-archived versionVielma, T., Uusi-Kyyny, P., Salminen, J., Alopaeus, V., & Lassi, U. (2019). Volumetric properties of aqueous solutions of zinc sulfate at temperatures from 298.15 to 393.15 K and pressures up to 10 MPa. Manuscript in preparation. https://doi.org/10.1021/acs.jced.0c00767Self-archived versionVielma, T., Hnedkovsky, L., Uusikyyny, P., Salminen, J., Alopeus, V., Hefter, G., & Lassi, U. (2019). Volumetric model for aqueous solutions of zinc sulfate from 293.15 to 393.15 K and up to 10 MPa. Manuscript in preparation. https://doi.org/10.1021/acs.jced.0c00768Self-archived versionVielma, T., Lassi, U., & Salminen, J. (2018). Precipitation of silica from zinc process solutions. Monatshefte für Chemie, 149, 313-321. https://doi.org/10.1007/s00706-017-2054-1Self-archived versionVielma, T., Salminen, J., & Lassi, U. (2019). Thermodynamics of CaSO4 and its hydrates in aqueous zinc sulfate media. Manuscript submitted for publication.TiivistelmäSinkki on yleinen metalli, ja sillä on keskeinen rooli sinkittyjen terästuotteiden, paristojen ja jopa lannoitteiden valmistuksessa. Sen tuotanto perustuu sinkkipitoisten mineraalien rikkihappoliuotukseen, muodostuneen prossessiliuoksen puhdistukseen ja lopulta metallisen sinkin elektrolyysitalteenottoon. Tässä työssä kehitettiin termodynaaminen malli teollisesti tärkeälle ZnSO₄-H₂SO₄-H₂O -systeemille. Malliparametrit määritettiin kirjallisuudessa esitetyistä tuloksista ja tässä työssä tehdyistä uusista jäätymispiste- ja tiheysmittauksista. Käyttämällä kaupallisia Gibbsin energian minimointialgoritmiin perustuvia ohjelmistoja, kuten ChemSheet tai FactSage, tässä työssä kehitetyllä mallilla voidaan helposti kuvata sinkkisulfaattipitoisten vesiliuosten faasitasapainoja ja laskea systeemin termodynaamisia ominaisuuksia. Malliin sisällytettyihin ominaisuuksiin kuuluvat systeemin komponenttien aktiivisuudet, entalpiamuutokset, lämpökapasiteetit sekä tiheydet laajalla lämpötila-, paine- ja rikkihapon pitoisuusalueella. Liuoksen epäideaalisuutta kuvattiin Pitzerin ioniaktiivisuusmallilla.Työssä sinkkisulfaattiliuoksille kehitettyä mallia testattiin kahdessa sinkintuotannon kannalta keskeisessä tapaustutkimuksessa. Amorfisen piidioksidin saostumista vahvahappoliuotuksen aikana tutkittiin kokeellisesti ja laskennallisesti. Amorfisen piidioksidin liukoisuus prosessiliuokseen ennustettiin onnistuneesti. Kipsinpoistoprosessin tutkimusta varten mallia laajennettiin lisäämällä siihen Ca²⁺-ioni. Mallilla laskettiin kipsin liukoisuus prosessiliuokseen. Saadut tulokset vastasivat hyvin käytännössä havaittuja arvoja.Tutkimuksen tuloksia on suoraan hyödynnetty sinkintuotantoprosessin ymmärtämisessä. Ne myös mahdollistavat jatkossa edistyneempien työkalujen kehittämisen niin prosessin hallintaan kuin tutkimukseenkin.OsajulkaisutOsajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.Vielma, T., Salminen, J., & Lassi, U. (2018). Thermodynamics of the ZnSO4–H2SO4–H2O system. CALPHAD, 60, 126-133. https://doi.org/10.1016/j.calphad.2017.12.006Rinnakkaistallennettu versioVielma, T., Salminen, J., & Lassi, U. (2019). Freezing point depression in the ternary ZnSO4-H2SO4-H2O system. The Journal of Chemical Thermodynamics, 132, 276–280. https://doi.org/10.1016/j.jct.2018.12.043Rinnakkaistallennettu versioVielma, T., Uusi-Kyyny, P., Salminen, J., Alopaeus, V., & Lassi, U. (2019). Volumetric properties of aqueous solutions of zinc sulfate at temperatures from 298.15 to 393.15 K and pressures up to 10 MPa. Manuscript in preparation. https://doi.org/10.1021/acs.jced.0c00767Rinnakkaistallennettu versioVielma, T., Hnedkovsky, L., Uusikyyny, P., Salminen, J., Alopeus, V., Hefter, G., & Lassi, U. (2019). Volumetric model for aqueous solutions of zinc sulfate from 293.15 to 393.15 K and up to 10 MPa. Manuscript in preparation. https://doi.org/10.1021/acs.jced.0c00768Rinnakkaistallennettu versioVielma, T., Lassi, U., & Salminen, J. (2018). Precipitation of silica from zinc process solutions. Monatshefte für Chemie, 149, 313-321. https://doi.org/10.1007/s00706-017-2054-1Rinnakkaistallennettu versioVielma, T., Salminen, J., & Lassi, U. (2019). Thermodynamics of CaSO4 and its hydrates in aqueous zinc sulfate media. Manuscript submitted for publication.Academic dissertation to be presented with the assent of the Doctoral Training Committee of Technology and Natural Sciences of the University of Oulu for public defence in the Wetteri auditorium (IT115), Linnanmaa, on 20 September 2019, at 12 noonAbstract
Zinc is a common metal, and has a central role in the production of galvanised bulk products, battery applications and fertilisers. Its production relies mainly on the leaching of zinc minerals with sulfuric acid, followed by purification and electrowinning. In this thesis an internally consistent thermodynamic model for the industrially important ZnSO₄-H₂SO₄-H₂O system was developed. Model parameters were optimised using available literature data and new experimental freezing point and density data determined in this work. With Gibbs energy minimisation algorithms embedded in commercial software, such as ChemSheet and FactSage, the developed model can be used to calculate easily phase equilibria and thermodynamic properties of aqueous zinc sulfate solutions and solid zinc sulfate phases, including activity coefficients, enthalpy changes, heat capacities, densities and solubilities, in a wide range of temperature, pressure and sulfuric acid concentrations. Solution non-ideality was treated with the original Pitzer model with electrostatic mixing terms included.
Applicability of thermodynamic approach and the developed model was demonstrated by two separate case studies on the hydrometallurgical zinc process. Precipitation of amorphous silica during hot acid leach was studied experimentally. Its solubility in the process solution was also successfully predicted using the thermodynamic approach. To study crystallisation of gypsum during the gypsum precipitation stage, the model was expanded by addition of the Ca²⁺ ion. The model calculations showed good agreement with the experienced Ca²⁺ levels.
The results of this thesis have found immediate use in understanding the various stages of the electrolytic zinc process. The obtained results also form a basis on which new, more advanced tools for managing and studying the process can be developed.Tiivistelmä
Sinkki on yleinen metalli, ja sillä on keskeinen rooli sinkittyjen terästuotteiden, paristojen ja jopa lannoitteiden valmistuksessa. Sen tuotanto perustuu sinkkipitoisten mineraalien rikkihappoliuotukseen, muodostuneen prossessiliuoksen puhdistukseen ja lopulta metallisen sinkin elektrolyysitalteenottoon. Tässä työssä kehitettiin termodynaaminen malli teollisesti tärkeälle ZnSO₄-H₂SO₄-H₂O -systeemille. Malliparametrit määritettiin kirjallisuudessa esitetyistä tuloksista ja tässä työssä tehdyistä uusista jäätymispiste- ja tiheysmittauksista. Käyttämällä kaupallisia Gibbsin energian minimointialgoritmiin perustuvia ohjelmistoja, kuten ChemSheet tai FactSage, tässä työssä kehitetyllä mallilla voidaan helposti kuvata sinkkisulfaattipitoisten vesiliuosten faasitasapainoja ja laskea systeemin termodynaamisia ominaisuuksia. Malliin sisällytettyihin ominaisuuksiin kuuluvat systeemin komponenttien aktiivisuudet, entalpiamuutokset, lämpökapasiteetit sekä tiheydet laajalla lämpötila-, paine- ja rikkihapon pitoisuusalueella. Liuoksen epäideaalisuutta kuvattiin Pitzerin ioniaktiivisuusmallilla.
Työssä sinkkisulfaattiliuoksille kehitettyä mallia testattiin kahdessa sinkintuotannon kannalta keskeisessä tapaustutkimuksessa. Amorfisen piidioksidin saostumista vahvahappoliuotuksen aikana tutkittiin kokeellisesti ja laskennallisesti. Amorfisen piidioksidin liukoisuus prosessiliuokseen ennustettiin onnistuneesti. Kipsinpoistoprosessin tutkimusta varten mallia laajennettiin lisäämällä siihen Ca²⁺-ioni. Mallilla laskettiin kipsin liukoisuus prosessiliuokseen. Saadut tulokset vastasivat hyvin käytännössä havaittuja arvoja.
Tutkimuksen tuloksia on suoraan hyödynnetty sinkintuotantoprosessin ymmärtämisessä. Ne myös mahdollistavat jatkossa edistyneempien työkalujen kehittämisen niin prosessin hallintaan kuin tutkimukseenkin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Alkali-activated materials containing mine tailings and zeolite for seepage water treatment in a closed nickel mine
Get PDFIn the present study, alkali-activated materials were assessed as adsorbents for mine water treatment. The composition of alkali-activated materials, involving mixtures of metakaolin, blast-furnace slag, mine tailings, and zeolite, was optimized based on their leaching behavior and adsorption performance. The most effective adsorbent contained solely blast furnace slag as an aluminosilicate precursor and was selected for a pilot-scale study at a closed nickel mine in Finland. In the pilot, seepage water from a gangue area with an influent flow rate of 0.5 m3/d was treated using a permeable reactive barrier set-up containing 10 kg of slag-based adsorbent prepared by a granulation-alkali activation process. During a one-week experiment, the adsorbent granules were capable of effectively uptaking Ni, Fe, and Mn from the seepage water; the removal percentages of Ni, Fe, and Mn were 82.4%, 81.6%, and 82.5%, respectively. The results indicated the feasibility of blast furnace slag-based adsorbents for toxic element removal in a potentially sustainable approach
Towards greener batteries: sustainable components and materials for next-generation batteries
Get PDFBatteries are the main component of many electrical systems, and due to the elevated consumption of electric vehicles and portable electronic devices, they are the dominant and most rapidly growing energy storage technology. Consequently, they are set to play a crucial role in meeting the goal of cutting greenhouse gas emissions to achieve more sustainable societies. In this critical report, a rational basic-to-advanced compilation study of the effectiveness, techno-feasibility, and sustainability aspects of innovative greener manufacturing technologies and processes that deliver each battery component (anodes, cathodes, electrolytes, and separators) is accomplished, aiming to improve battery safety and the circularity of end-products. Special attention is given to biomass-derived anode materials and bio-based separators utilization that indicates excellent prospects considering green chemistry, greener binders, and energy storage applications. To fully reach this potential, one of the most promising ways to achieve sustainable batteries involves biomass-based electrodes and non-flammable and non-toxic electrolytes used in lithium-ion batteries and other chemistries, where the potential of a greener approach is highly beneficial, and challenges are addressed. The crucial obstacles related to the successful fabrication of greener batteries and potential future research directions are highlighted. Bridging the gap between fundamental and experimental research will provide critical insights and explore the potential of greener batteries as one of the frontrunners in the uptake of sustainability and value-added products in the battery markets of the future
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Improved circularity by manganese upgrading from secondary material flows
No full textAbstract
The rapidly expanding battery market is driving increased demand for battery-grade chemicals, including manganese sulfate and lithium salts. Furthermore, recent EU battery legislation mandates improved recycling efficiencies and mandates that future batteries contain defined proportions of recycled critical elements. Consequently, the importance of secondary raw materials—beyond battery black mass—is expected to increase.
This thesis investigates the recovery of manganese from manganese-rich residues produced by the zinc industry. In sulfate media, manganese was successfully purified from this industrial side stream. The resulting concentrated manganese sulfate solution was further processed, although minor impurities such as potassium, zinc, calcium, and magnesium remained. A combination of washing, sulfide precipitation, and sulfuric acid-assisted crystallization was employed to purify the leachate and produce battery-grade MnSO4·H2O crystals. In addition, NCM811 cathode active materials (CAMs) were precipitated from partially purified manganese solutions and compared with a reference CAM sample.
The second part of the thesis focuses on lithium recovery from various CAMs using a NiSO4 solution under hydrothermal conditions. This method can be integrated with the manganese recovery process by using delithiated CAM as an oxidizing agent for manganese. Delithiation was performed either in situ or prior to acid leaching, and the delithiated CAM was then used to oxidize the manganese. Both approaches achieved lithium recovery yields exceeding 95%. Notably, hydrothermal delithiation offers advantages over acid leaching, as it selectively dissolving lithium and precipitating nickel into the solid residue. Original papers Kauppinen, T., Vielma, T., Salminen, J., & Lassi, U. (2020). Selective recovery of manganese from anode sludge residue by reductive leaching. ChemEngineering, 4(2), 40. https://doi.org/10.3390/chemengineering4020040 https://doi.org/10.3390/chemengineering4020040 Self-archived version Kauppinen, T., Rautio, L., Flores, A.H., Manninen, M., Hu, T., Salminen, J., Vielma, T., & Lassi, U. (2025). Purification of the manganese sulfate solution obtained from manganese sludge using sulfide precipitation and sulfuric acid-assisted crystallization. Manuscript in preparation. Kauppinen, T., Flores, A.H., Laine, T., Vielma, T., Hu, T., Salminen, J., & Lassi, U. (2025). Selective recovery of lithium from cathode active material under hydrothermal conditions. Manuscript in preparation. Kauppinen, T., Vielma, T., Salminen, J., Manninen, Hu, T., & Lassi, U. (in press). Utilization of Nirich NCM cathode material as an oxidation chemical to control manganese in Li-ion battery waste recycling. https://doi.org/10.1016/j.hydromet.2026.106647 https://doi.org/10.1016/j.hydromet.2026.106647 Kauppinen, T., Laine, P., Välikangas, J., Tynjälä, P., Hu, T., Salminen, J., & Lassi, U. (2023). Co‐precipitation of NCM 811 using recycled and purified manganese: Effect of impurities on the battery cell performance. ChemElectroChem, 10(17), e202300265. https://doi.org/10.1002/celc.202300265 https://doi.org/10.1002/celc.202300265 Self-archived version Tiivistelmä
Akkuteollisuuden kasvu lisää akkulaatuisten kemikaalien, kuten mangaanisulfaatin ja litiumsuolojen, kysyntää. EU:n uusi akkudirektiivi edellyttää lisäksi nykyistä korkeampia kierrätystehokkuuksia ja määrittää, että uusiin akkuihin on sisällytettävä määritelty osuus kierrätettyjä raaka-aineita. Tämän seurauksena perinteisen mustamassan ohella myös muiden sekundääristen raaka-aineiden merkityksen odotetaan kasvavan.
Tässä väitöskirjatutkimuksessa keskityttiin mangaanin talteenottoon sinkkiteollisuuden mangaanipitoisesta sivuainevirrasta, josta mangaani erotettiin onnistuneesti sulfaattiliuoksessa. Liuotuksesta saatua väkevää mangaanisulfaattiliuosta oli puhdistettava, koska se sisälsi edelleen pieniä pitoisuuksia epäpuhtauksia, kuten kaliumia, sinkkiä, kalsiumia ja magnesiumia. Liuoksen puhdistukseen käytettiin pesua, sulfidisaostusta ja rikkihappoavusteista kiteytystä, jolloin liuoksesta saatiin erotettua akkulaatuisia MnSO4·H2O kiteitä. Lisäksi NCM811-katodiaktiivimateriaalia valmistettiin osittain puhdistetuista mangaanisulfaattiliuoksista ja verrattiin puhtaasta mangaanisulfaatista valmistettuun referenssimateriaaliin.
Väitöskirjan toisessa osassa litium liuotettiin selektiivisesti katodimateriaaleista hydrotermisissä olosuhteissa nikkelisulfaattiliuosta hyödyntäen. Tämä menetelmä voidaan integroida mangaanin talteenottoprosessiin hyödyntämällä delitioitua katodimateriaalia mangaanin hapettimena. Delitiointi suoritettiin joko in-situ tai etukäteen happoliuotuksella, minkä jälkeen delitioitua katodimateriaalia käytettiin mangaanin hapettamiseen. Molemmissa tavoissa saavutettiin yli 95-prosenttinen litiumin saanto. Hydroterminen delitiointi tarjosi happoliuotukseen verrattuna etuja liuottamalla litiumin selektiivisesti sekä saostamalla nikkeliä liuoksesta kiinteään jäännökseen. Osajulkaisut Kauppinen, T., Vielma, T., Salminen, J., & Lassi, U. (2020). Selective recovery of manganese from anode sludge residue by reductive leaching. ChemEngineering, 4(2), 40. https://doi.org/10.3390/chemengineering4020040 https://doi.org/10.3390/chemengineering4020040 Rinnakkaistallennettu versio Kauppinen, T., Rautio, L., Flores, A.H., Manninen, M., Hu, T., Salminen, J., Vielma, T., & Lassi, U. (2025). Purification of the manganese sulfate solution obtained from manganese sludge using sulfide precipitation and sulfuric acid-assisted crystallization. Manuscript in preparation. Kauppinen, T., Flores, A.H., Laine, T., Vielma, T., Hu, T., Salminen, J., & Lassi, U. (2025). Selective recovery of lithium from cathode active material under hydrothermal conditions. Manuscript in preparation. Kauppinen, T., Vielma, T., Salminen, J., Manninen, Hu, T., & Lassi, U. (in press). Utilization of Nirich NCM cathode material as an oxidation chemical to control manganese in Li-ion battery waste recycling. https://doi.org/10.1016/j.hydromet.2026.106647 https://doi.org/10.1016/j.hydromet.2026.106647 Kauppinen, T., Laine, P., Välikangas, J., Tynjälä, P., Hu, T., Salminen, J., & Lassi, U. (2023). Co‐precipitation of NCM 811 using recycled and purified manganese: Effect of impurities on the battery cell performance. ChemElectroChem, 10(17), e202300265. https://doi.org/10.1002/celc.202300265 https://doi.org/10.1002/celc.202300265 Rinnakkaistallennettu versio Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Technology and Natural Sciences of the University of Oulu for public defence in Ulappa, Kokkolan yliopistokeskus Chydenius, on 20 February 2026, at 12 noonAbstract
The rapidly expanding battery market is driving increased demand for battery-grade chemicals, including manganese sulfate and lithium salts. Furthermore, recent EU battery legislation mandates improved recycling efficiencies and mandates that future batteries contain defined proportions of recycled critical elements. Consequently, the importance of secondary raw materials—beyond battery black mass—is expected to increase.
This thesis investigates the recovery of manganese from manganese-rich residues produced by the zinc industry. In sulfate media, manganese was successfully purified from this industrial side stream. The resulting concentrated manganese sulfate solution was further processed, although minor impurities such as potassium, zinc, calcium, and magnesium remained. A combination of washing, sulfide precipitation, and sulfuric acid-assisted crystallization was employed to purify the leachate and produce battery-grade MnSO4·H2O crystals. In addition, NCM811 cathode active materials (CAMs) were precipitated from partially purified manganese solutions and compared with a reference CAM sample.
The second part of the thesis focuses on lithium recovery from various CAMs using a NiSO4 solution under hydrothermal conditions. This method can be integrated with the manganese recovery process by using delithiated CAM as an oxidizing agent for manganese. Delithiation was performed either in situ or prior to acid leaching, and the delithiated CAM was then used to oxidize the manganese. Both approaches achieved lithium recovery yields exceeding 95%. Notably, hydrothermal delithiation offers advantages over acid leaching, as it selectively dissolving lithium and precipitating nickel into the solid residue.Tiivistelmä
Akkuteollisuuden kasvu lisää akkulaatuisten kemikaalien, kuten mangaanisulfaatin ja litiumsuolojen, kysyntää. EU:n uusi akkudirektiivi edellyttää lisäksi nykyistä korkeampia kierrätystehokkuuksia ja määrittää, että uusiin akkuihin on sisällytettävä määritelty osuus kierrätettyjä raaka-aineita. Tämän seurauksena perinteisen mustamassan ohella myös muiden sekundääristen raaka-aineiden merkityksen odotetaan kasvavan.
Tässä väitöskirjatutkimuksessa keskityttiin mangaanin talteenottoon sinkkiteollisuuden mangaanipitoisesta sivuainevirrasta, josta mangaani erotettiin onnistuneesti sulfaattiliuoksessa. Liuotuksesta saatua väkevää mangaanisulfaattiliuosta oli puhdistettava, koska se sisälsi edelleen pieniä pitoisuuksia epäpuhtauksia, kuten kaliumia, sinkkiä, kalsiumia ja magnesiumia. Liuoksen puhdistukseen käytettiin pesua, sulfidisaostusta ja rikkihappoavusteista kiteytystä, jolloin liuoksesta saatiin erotettua akkulaatuisia MnSO4·H2O kiteitä. Lisäksi NCM811-katodiaktiivimateriaalia valmistettiin osittain puhdistetuista mangaanisulfaattiliuoksista ja verrattiin puhtaasta mangaanisulfaatista valmistettuun referenssimateriaaliin.
Väitöskirjan toisessa osassa litium liuotettiin selektiivisesti katodimateriaaleista hydrotermisissä olosuhteissa nikkelisulfaattiliuosta hyödyntäen. Tämä menetelmä voidaan integroida mangaanin talteenottoprosessiin hyödyntämällä delitioitua katodimateriaalia mangaanin hapettimena. Delitiointi suoritettiin joko in-situ tai etukäteen happoliuotuksella, minkä jälkeen delitioitua katodimateriaalia käytettiin mangaanin hapettamiseen. Molemmissa tavoissa saavutettiin yli 95-prosenttinen litiumin saanto. Hydroterminen delitiointi tarjosi happoliuotukseen verrattuna etuja liuottamalla litiumin selektiivisesti sekä saostamalla nikkeliä liuoksesta kiinteään jäännökseen
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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